Locking mechanisms for oilfield equipment often include a cylindrical locking mechanism called a dog. The dog is put into a locking position between two components, such as a tension ring and a housing, to hold a position or take a load. For example, the dog can be part of a tension ring that can maintain a riser in stable tension when offshore platforms heave. When the riser is retrieved, the dog can be locked to a housing located on the riser to prevent it from falling and injuring personnel. An additional dog can lock onto another component for storage.
To prevent the accidental unlocking of the dogs, a manual lockout can be employed to secure the dog in a locked position. When the lockout is engaged, the dog is locked in an engaged position. When the lockout is disengaged, the dog is free to move between an engaged and a disengaged position. However, the actual position of the dog is unknown. For example, when a lockout is disengaged, the dog may still be in the engaged position. This may cause problems for the operators.
A need exists for a technique to manually lockdown dogs and indicate whether a dog is in a locked or unlocked position. The following technique may solve these problems.